Comparison of ozonation and distillation as treatment methods of recycled water for bioethanol fermentation process

The aim of this study was to compare an evaporation and oxidation as a final stage of stillage treatment to recycle the treated water and use it in the ethanol process, namely the fermentation process. This comparison was made by analyzing the ethanol yield of all samples, with additional analysis of chemical parameters like COD, N-HH3 and PO4 3− content to check their influence in the ethanol yield.

The paper compared the performance of the ethanol yield after alcoholic fermentation with samples of rejected (RW) and permeate water (PW), RW and PW treated by oxidation with ozone (O3) (5 and 15 min) and evaporation, aiming the recirculation back to the bioethanol process. RW and PW were collected after an anaerobic bioreactor (AnBR) used for stillage treatment.

Nine types of fermentations were made, where one used 100% tap water (control) and the remaining used 80% of recycled water and 20% of tap water.

Comparing with the control (15.68%), evaporated permeate water and permeate water oxidized for 15 min achieved the highest and closest ethanol concentrations in v/v with 14.68 and 14.08% respectively. RW and PW had the lowest ethanol results with 8.43 and 8.68%.

The studied methods for water treatment are effective to recycle water taking into consideration the ethanol yield, allowing a good possibility of recirculation. Chemical oxygen demand, ammonia nitrogen and phosphate content did not strongly affect the ethanol yield in all samples treated, with similar results.

Oxidation was more environmental friendly and cheaper if performed in 5 min. Further research in the monitoring of the fermentation, ethanol quality and in the number of cycles of fermentation with recycled water is needed.

Fernandes A., Boczkaj G., Głazowska J., Tomczak-Wandzel R., Kamiński M., (2017), Comparison of ozonation and distillation as treatment methods of recycled water for bioethanol fermentation process, Waste Biomass Valorization, DOI 10.1007/s12649-017-9888-y